1. Field of the Invention
The present invention relates to an ozonizer for generating ozone from the oxygen contained in air, and more particularly, to an ozonizer well adapted for use in 24-hour working baths, circulating water purifiers such as a Jacuzzi, ozonized water generators, water purifiers and the like. Furthermore, the present invention relates to a water purifier equipped with an ozonizer for use with 24-hour working baths, Jacuzzis, ponds, water tanks and pools, and to a method of cleaning the ozonizer.
2. Description of the Related Art
Ozone has conventionally been used in industrial as well as household applications for purifying and deodorizing water and the like. A relatively small-sized apparatus for generating ozone for household use employs a creeping discharge element including a filamentary discharge electrode and a surface induction electrode disposed opposite each other and a dielectric layer interposed therebetween. A voltage is applied between the electrodes to thereby excite discharge on the filamentary discharge electrode. This type of creeping discharge element is disclosed, for example, in U.S. Pat. No. 4,652,318.
More particularly, such ozonizers include a creeping discharge element, a power circuit and a resin case for housing the creeping discharge element and power circuit. The creeping discharge element is typically composed of a dielectric layer formed from ceramic, a filamentary discharge electrode disposed on one surface of the dielectric layer, and a surface induction layer disposed on the other surface of the dielectric layer opposite the filamentary discharge electrode. The power circuit applies a voltage between the filamentary discharge electrode and surface induction electrode so as to excite a discharge from the filamentary discharge electrode.
In Japanese Patent Application Laid-Open (kokai) No. 8-171979, the present applicant proposed an ozonizer employing a creeping discharge element for use in the circulating water purifier of a 24-hour working bath. This ozonizer is described below with reference to FIGS. 8A-8D. FIG. 8B shows a plan view of the ozonizer 310. FIG. 8A shows a plan view of a cover 330 that attaches to the ozonizer. FIG. 8C shows the ozonizer of FIG. 8B as viewed in the direction of arrow C of FIG. 8B. FIG. 8D shows a sectional view along line 8D--8D of FIG. 8B.
As shown in FIG. 8D, a creeping discharge element, i.e. an ozonizing element, is formed as part of a high-voltage generating board 350 including a high-voltage-generating circuit element 352. Specifically, the high-voltage generating board 350 is formed from a dielectric having a surface induction electrode 366 embedded in a portion thereof and a filamentary discharge electrode 368 disposed on the top surface thereof. The high-voltage generating board 350 is disposed within a housing 320 such that the filamentary discharge electrode 368 mounted on the high-voltage generating board 350 faces an opening 320a formed in the housing 320. The cover shown in FIG. 8A is attached to the housing 320 so as to close the opening 320a, to thereby prevent ozone leakage from the housing 320.
Large-sized creeping discharge type ozonizers for industrial use employ pure oxygen or dry air as a starting material, whereas small-sized ozonizers for household use employing the above-described creeping discharge element use untreated air as a starting material. Accordingly, small-sized ozonizers are disadvantageous in that when the creeping discharge element is used continuously, the material of the creeping discharge element reacts with nitrogen or the like in air to form an ammonium salt on the element surface. The ammonium salt hinders creeping discharge with a resulting failure in the proper generation of ozone. Thus, for such small-sized creeping discharge type ozonizers, it is important to check whether ozone continues to be generated. Hitherto, this checking was difficult to conduct.
More particularly, because untreated air has a humidity higher than that of artificially-produced dry air, large amounts of nitrogen oxides are produced when ozone is generated by discharge.
The nitrogen oxides chemically react with ammonia present in the air to produce ammonium nitrate. The thus-produced ammonium nitrate covers the filamentary discharge electrode.
Accordingly, the density of the electric field generated by the filamentary discharge electrode is reduced. Also, ammonium nitrate covering the filamentary discharge electrode absorbs water present in the air and becomes electrically conductive, thus increasing the apparent area of the filamentary discharge electrode. As a result, the capacitance of the dielectric increases.
That is, in a conventional ozonizer, because ammonium nitrate covers the filamentary discharge electrode, the density of the electric field generated by the filamentary discharge electrode is reduced. The capacitance of the dielectric increases, resulting in reduced ozone generation.
Conventionally, therefore, the ozonizer is disassembled, and adhering ammonium nitrate is wiped off from the filamentary discharge electrode using water or a solvent. That is, a conventional ozonizer must be maintained through manual labor.
After cleaning, the creeping discharge element resumes discharging to thereby generate ozone. However, a high electric potential of several kilovolts is applied to the creeping discharge element even though the current flowing through the element is very small. Therefore, it is dangerous for an ordinary household user to clean the element. That is, even though designed for household use, conventional ozonizers are difficult to maintain.